S197 Spring and Sway Bar Rates

Discussion in 'Suspension and Chassis' started by Grant 302, Dec 13, 2017.

  1. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    S197 Springs Front/Rear:
    OEM:
    Boss 302 ................... 148F/186R lbs/in
    Boss 302 Laguna Seca 137F/191R lbs/in
    Brembo GT/ GTPP ...... 131F/167R lbs/in
    GT and V6PP............... 123F/156R lbs/in
    P Springs (1" drop) 230-260/202 (est - may be same as published K below)
    K Springs (1.5" drop) M-5300-KA Front: 228 lb/in. Rear: 199.5 lb/in.
    T Springs (0.6/1.4" drop Boss reference) M-5300-T Front: ??? Rear: 199.5 lb/in. (uses K spring rear)
    GT500 -

    Aftermarket:
    Steeda Ultra Lites 555-8206 (1.25/1.5" drop) - 195lb front, 175lb rear
    Steeda Sport Springs 555-8215 (1.0/1.25" drop) - 200lb front, 175lb rear
    Steeda Comp Springs Boss 302 555-8245 (0.2"/0.8" drop-Boss reference) - 225lb front, 195lb rear
    Eibach sportline 4.12535 (1.6"/2") Front: 183 lb/in. Rear: 103-217 lb/in.
    Eibach Pro kit GT/Boss 35125.140 (1.0/1.5" drop)
    Eibach Pro kit 35101.140 '05-10GT/'10V6 Front: 171-228 lb/in. Rear: 180 lb/in.
    MM R&T Lowering Coupe 435H0 (1.9/2" drop) 320-360F / 260-380R ('vert same rates)
    H&R Super Sport 51655-77 (1.7/1.9 drop) ~250lb/in / rear: ~200lb/in
    H&R Race 51655-88 (1.5/1.4 drop) ~300lb/in / rear: ~275lb/in
    BMR Lowering SP009 (1.5" drop) 165 lb. - Front, 160 lb. - Rear
    BMR Handling SP065 (1.5" drop) 240 lb/in front (linear), 200 lb/in rear (dual-rate)
    BMR Handling SP072 (1.5" drop w/GT500)(~0.5"F/~1"R on GT) 260 lb/in front (linear), 220 lb/in rear (dual-rate)
    SR Performance (1.5" drop) Front: 230 lb/in. Rear: 200 lb/in.
    Pedders SportsRyder 1" lowering F: 200.8 lb/in R: 186.2 lb/in


    FRONT S197 Bars:
    34.6mm GT/Boss/LS .................. 436 lbs/in
    34mm '05-'10GT/GT500/'11 V6 ... 385 lbs/in
    33.2mm '12+ V6
    28.6mm 2010 V6
    Ford 35mm 'Blue' bar M-5490-AF (Part of M-5490-A kit)
    Eibach 36mm: 340, 400, 450 lbs/in
    BMR-SB022 35mm: 441, 506, 587 lbs/in
    BMR-SB041 38mm: 706, 788, 886, 1002, 1144 lbs/in
    Strano Performance 35mm hollow: 472, 547, 642 lbs/in

    REAR S197 Bars:
    Ford 13mm Solid (Boss 302S):............ 18 lbs/in
    Ford 18mm Solid (Convertible):........... 55 lbs/in
    Ford 20mm Solid (2005-2010 GT):....... 96 lbs/in
    Ford 22mm Solid (2011+ V-6):........... 147 lbs/in
    Ford 23mm Solid
    Ford 24mm Solid (2011+ 5.0, GT500): 193 lbs/in
    Ford 25mm Solid (Boss 302):............. 250 lbs/in
    Ford 26mm Solid (Laguna Seca):........ 275 lbs/in
    Ford 22mm 'Blue' bar M-5490-AR (Part of M-5490-A kit)

    Eibach 25mm: 130, 145, 175 lbs/in
    Strano Performance Parts 8419 1" tubular: 162, 185, 225 lbs/in
    BMR-SB023: 146 lbs/in
    BMR-SB042 25mm: 224, 259, 302, 356 lbs/in
    Whiteline 27mm 'calculated' from stated increase over 24mm?GT bar: 266, 309, 357, 411 lbs/in

    Been meaning to do this for a while now...
    Please post any additions and corrections, I'll get to updating and reformatting as info gets added.
     
    Last edited: Dec 14, 2017
  2. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    Reserved space for sway bar/spring math.
     
  3. Tri-bar

    Tri-bar TMO Race

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    Eibach 25mm Rear tubular (2011+ GT, Brembo, Boss): 130, 145, 170 lbs/in
     
    Last edited: Dec 13, 2017
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  4. Norm Peterson

    Norm Peterson Corner Barstool Sitter

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    BMR "Handling" springs - 1.5" lowering, 240 lb/in front (linear), 200 lb/in rear (dual-rate) . . . Part # Sp065

    It may still be possible to get "GT500 Handling springs", Part# SP072, which are 260 lb/in front (linear) and 220 lb/in rear (dual-rate). Searching by part number still finds them. Front lowering on a "regular GT" is only a little over 0.5" and the rear lowering is a little over an inch, maybe as much as an inch and an eighth.


    Norm
     
    Last edited: Dec 14, 2017
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  5. 302 Hi Pro

    302 Hi Pro Boss 302 - Racing Legend to Modern Muscle Car

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    Reserved space to advise @Grant302:

    Outstanding Post, excellent information.

    Thank you
     
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  6. Norm Peterson

    Norm Peterson Corner Barstool Sitter

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    Thanks for making me look at it again - it still needed another edit (red text).


    Norm
     
  7. Fabman

    Fabman Project: "Frankenstang"

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    This is awesome.
    I didn't see the FRPP front blue bar on there though...
     
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  8. Big Black

    Big Black Good, fast<del>, and cheap</del>

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    I don't see it either...P# M-5490-A is the kit - 35mm front, 22mm 'Blue Bar' rear.
     
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  9. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    All the 'drop' figures are from GT/coupe - unless noted otherwise.

    Only because I have no data on it.

    LOL. Thanks Dave! Only took me 3.75 *years* from when I originally thought to do so.
     
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  10. Norm Peterson

    Norm Peterson Corner Barstool Sitter

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    Understood. On a GT500, the SP072 kit claims 1.5" lowering.

    Add another even later edit above. Dammit.


    Norm
     
  11. Senna1

    Senna1 TMO Beginner

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    I know this is an older thread, just curious if this is updated information from somewhere? I've seen rates of ~200/165 quoted for the P springs up until now. Including, I think, Vorshlag's testing (I have no test data myself to contribute/confirm).
     
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  12. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    That's a good question, and part of what I intend(ed) to follow up with the spring and sway bar math.

    If you look at the chart from Vorshlag:
    [​IMG]

    ...then look at the delta in force between two values one inch apart near the corner weight of the vehicle, you can see that the force delta is closer to the values that I estimate. I would consider these to be 'working' values since they are the relevant rate for dual-rate or progressive springs.

    For example:
    Stock front weight is ~1,000 lbs per corner. Looking at the positions 1/2" above and below that, there are force values of 1,167 and 923. The difference between the two is 244 lb./in. Checking the pair of values directly below those two are 1,037 and 806. Difference there is 231 lb./in.

    Sme thing for the rear near 800 lb. corner weight gets 202 and 203 lb./in.

    It seems to me that the 'target'/published rates for the K springs are about the same as I've estimated. Assuming some variability in the above test data, it seems reasonable that is the design intent to use the same rates.
     
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  13. Norm Peterson

    Norm Peterson Corner Barstool Sitter

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    Agreed ↑↑↑ . Average rate from the zero force point isn't very useful if there's much progression.

    That front spring could realistically be advertised at 140 - 250 and the rear at 100 - 205 without being off by enough to matter.


    Norm
     
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  14. Senna1

    Senna1 TMO Beginner

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    Geez... I've looked at that testing chart probably a dozen times now over the course of a couple years without ever catching that the "Rate at position" column numbers at ride height are significantly lower than if you calculate the force deltas yourself.

    Thanks for spelling it out!
     
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  15. modernbeat

    modernbeat TMO Advanced

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    That "rate at position" is what it takes to move the spring the next half inch, up or down.
     
  16. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    That's what it *should* be. But the values shown are the total force divided by the total displacement. 1,197lb / 6" = 194.5...and 195 is on the chart in the "rate at position" column.
     
  17. Norm Peterson

    Norm Peterson Corner Barstool Sitter

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    ↑↑↑ Exactly.

    But the rates as tabulated are taken as the force in lbs at each displacement divided by that displacement. Which would be correct for a linear spring (and all of the rates would be the same).

    I'm going to guess that the cells containing the first displacement to be subtracted (the zero cells) were accidentally given absolute addressing and the formula then copied into every other rate cell. Here's what running the rate calcs from 0.5" below to 0.5" above provide for mean rates. You get the same answer if you work with 0.5" under and the stated displacement going up and average that with the result from 0.5" above and the stated displacement coming down.

    0.0

    0.5 75 140

    1.0 140 146

    1.5 221 163

    2.0 303 175

    2.5 396 188

    3.0 491 201

    3.5 597 204

    4.0 695 209

    4.5 806 228

    5.0 923 231

    5.5 1037 244

    6.0 1167



    Norm
     
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  18. modernbeat

    modernbeat TMO Advanced

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    The actual formula for that is to subtract the force value above from the force value below. To calculate the "Rate at position" for 2" of compression at the front, I subtract the force at 1.5" from the force at 2.5" (396-221) to come up with the 152. For very linear springs, it's very close to dividing the total force by total displacement. For progressive springs it give us more useful data.
     
  19. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    Yes, that's what the chart *should* show, but it does not. 396-221=175, and 175 should be on the chart, not 152.
     
  20. modernbeat

    modernbeat TMO Advanced

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    Dangit. I just realized that's an old graphic. I've got the file open on my computer and it says 175. That's where I went to find the formula. We used to use a different formula, and I'd guess that graphic was from that time.
     
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